1. Field of the Invention
The present invention relates to a bolt tightening tool for tightening a nut onto a bolt, and more particularly to a bolt tightening tool in which an outer sleeve adapted to receive the nut and an inner sleeve adapted to receive a bolt-tip provided at the extreme end of the bolt are rotated in the directions opposite to each other to produce shearing force on the bolt-tip which in turn is used to tighten the nut onto the bolt.
2. Description of the Prior Art
In a conventional bolt tightening tool shown in FIG. 1, an inner sleeve i adapted to receive a bolt-tip projecting from the bolt end for rotational drive therewith is axially movably disposed within an outer sleeve o adapted to receive a nut for rotational drive therewith. The outer sleeve o rotates and tightens the nut, and the bolt tip inserted in the inner sleeve i is sheared through the reaction force produced during the tightening operation so as to increase the bolt tightening force. In such a construction, however, even when the inner sleeve i receives the end portion of the bolt-tip inadequately, the outer sleeve o receives the nut to rotate it, causing failure or deformation of the end portion of the inadequately received bolt-tip which disadvantageously results in reduction of the tightening force and workers' accidents.